MATLAB Function Reference

evalin

Execute a string containing a MATLAB expression in a workspace

Syntax

• evalin(ws,expression)
  [a1,a2,a3,...] = evalin(ws,expression)
  evalin(ws,expression,catch_expr) 
  

Description

evalin(ws,expression) executes expression, a string containing any valid MATLAB expression, in the context of the workspace ws. ws can have a value of 'base' or 'caller' to denote the MATLAB base workspace or the workspace of the caller function. You can construct expression by concatenating substrings and variables inside square brackets:

• expression = [string1,int2str(var),string2,...]
  

[a1,a2,a3,...] = evalin(ws,expression) executes expression and returns the results in the specified output variables. Using the evalin output argument list is recommended over including the output arguments in the expression string:

• evalin(ws,'[a1,a2,a3,...] = function(var)')
  

The above syntax avoids strict checking by the MATLAB parser and can produce untrapped errors and other unexpected behavior.

evalin(ws,expression,catch_expr) executes expression and, if an error is detected, executes the catch_expr string. If expression produces an error, the error string can be obtained with the lasterr function. This syntax is useful when expression is a string that must be constructed from substrings. If this is not the case, use the try...catch control flow statement in your code.

Remarks

The MATLAB base workspace is the workspace that is seen from the MATLAB command line (when not in the debugger). The caller workspace is the workspace of the function that called the M-file. Note, the base and caller workspaces are equivalent in the context of an M-file that is invoked from the MATLAB command line.

Examples

This example extracts the value of the variable var in the MATLAB base workspace and captures the value in the local variable v:

• v = evalin('base','var');
  

Limitation

evalin cannot be used recursively to evaluate an expression. For example, a sequence of the form evalin('caller','evalin(''caller'',''x'')') doesn't work.

See Also

assignin, catch, eval, feval, lasterr, try

evalc

eventlisteners (COM)